Growings On: Spring-flowering bulbs can be planted from October through late December

Published 8:00 am Thursday, September 23, 2021

Morning temperatures requiring a sweater or jacket confirm the transition from summer to autumn. In fact, Sept. 22 marks the astronomical transition identified as the equinox.

At 3:21 p.m. Eastern Daylight Time, the Earth’s equator will be exactly beneath the sun. Earth’s orbit around the sun and the 23 and one-half degree tilt of its axis combine to provide the predictable change in daylength and corresponding pattern of seasons for regions away from the equator.

This orderly and dependable progression means that the sun will migrate from due east to due west on the equinox. If precise orientation of your home or another favorite location would be helpful, identifying a landmark corresponding to the sun’s position at sunrise and/or sunset would mark those cardinal directions.

Plants also respond in predictable ways to cooling temperatures and decreasing daylength. Their transition toward winter dormancy marks a useful time to install many perennial plants and also signals a good time to plant or to divide and replant spring-blooming bulbs.

Plants such as tulips, daffodils, hyacinths and crocuses are among the first flowers to appear in spring. Just as falling leaves mark the beginning of winter, the flowering of bulbs signals that cold weather is on the way out and warmer days are coming. In Georgia, spring-flowering bulbs can be planted from October through late December.

Before preparing the soil, select high-quality bulbs. Choose only bulbs that are firm, not soft, and are medium/large sized.

Bulbs of different types vary in size. For example, tulip bulbs are much larger than crocus bulbs. But a large tulip bulb is generally healthier than a small tulip bulb.

Bulbs should be firm and have unblemished skin. If bulbs are obtained by mail or online and cannot be inspected, purchasing from a reputable company will help ensure receiving a quality product.

Bulbs should be kept in a cool, dry, dark place until planting. Be wary of bulbs stored for long periods of time in less desirable conditions. Find a good spot to store them between purchasing and planting if you can’t plant them right away.

A soil pH of 6.0 to 6.8 is best for most bulbs. Incorporate lime if a soil test indicates a need for it. In the absence of a soil test, add one to two pounds of 5-10-10, 10-10-10 or 8-8-8 fertilizer per 100 square feet of bed space. Incorporate lime, fertilizer and any soil amendments thoroughly and deeply. Do not attempt to work the soil when it is too wet.

Planting depth and spacing are also important for the success of bulbs. A general rule of thumb for planting depth (from the top of the bulb to the soil surface) is two to three times the greatest diameter for bulbs two inches or more in diameter, and three to four times the greatest diameter for smaller bulbs.

Spacing will vary from one or two inches to as much as several feet. When spacing bulbs, consider not only how much space each plant needs, but also how frequently it will be dug up and divided. Also consider the landscape effect. The flower display is most effective when bulbs are planted in large clusters in confined areas rather than in evenly-spaced lines or sparse plantings throughout a large area.

Plant bulbs upright and press the soil firmly around them. Rhizomes and tuberous roots are usually planted on their sides. Water the beds thoroughly to help settle the soil.

An option for winter color might be to bring bulbs indoors to bloom earlier than they normally would outdoors. Crocus, galanthus, hyacinth, narcissus, daffodil, scilla and tulip are the easiest to force.

Pot bulbs in October or November using a well-drained soil. The number of bulbs per pot will vary according to pot and bulb size. Keep them in the dark at about 40 degrees Fahrenheit for eight to 12 weeks in a cold frame outdoors, an unheated garage or basement, or in your refrigerator. The bulbs must not be allowed to freeze.

After two or three months, the root system should be extensively developed, and shoots will start to emerge from the bulbs. Place the pots in a cool, bright room at about 55 degrees. If possible, place them in a southern window. Eastern or western windows are second best. Once shoots emerge, bulbs will produce blooms in about one month.

University of Georgia Extension Bulletin 918, “Flowering Bulbs for Georgia Gardens,” provides comprehensive guidance about choosing, planting and maintaining flowering bulbs.

Roger Gates is the agricultural and natural resources agent for University of Georgia Extension, Whitfield County. Contact him at roger.gates@uga.edu.